The flow measuring devices normally utilized in the pipeline and process industries, such as venturi meters, pitot tubes, and orifice meters, must be calibrated to insure accuracy, as the performance of each varies with the individual fluid properties. Current meter calibration techniques often rely upon positive displacement methods to assure precision. One of said techniques includes the use of a length of pipe having a piston or ball positioned therein with an external diameter substantially equal to the inner pipe diameter. The movement of the piston or ball by the fluid flow through the pipe provides a convenient and accurate check of the volume flow rate. When a metallic piston is used, detection of the position of the piston as it moves along the length of the pipe may be made by electrical or electronic means. When a flexible ball of material, such as rubber, is utilized as a piston, the detection must be by some physical means since the rubber ball would not ordinarily be useful in activating any type of electronic or magnetic detector. This invention provides a means of physically detecting the passage of a piston, such as a rubber ball, in a pipe.
It is therefore an object of this invention to provide a piston detector switch adaptable for use in conjunction with a pipe, to detect the passage of a piston through said pipe.
Another object of this invention is to provide a detector switch which is readily adaptable for field mounting on a pipe with a minimum amount of work and which does not require precise pipe orifices.
Another object of this invention is to provide a detector switch which may be made of readily available and inexpensive components and which may, therefore, be economically constructed.
Another object of this invention is to provide a piston detector switch having improved means of adjusting a switch relative to the actuating mechanism whereby the switch may be accurately calibrated to indicate the passage of a piston thereby.